Robert Morton, chief executive at the East of England Ambulance Trust (EEAST) made the announcement in a post on a staff website yesterday evening.

Mr Morton took over at EEAST in August 2015 after interim chief executive Dr Anthony Marsh stepped down.

But he has come under much criticism in recent months from unions and MPs as the trust struggled to cope with winter pressures and found itself in the middle of a whistleblowing scandal.

EEAST answered up to 3,200 calls a day during winter 2017/18 and frontline staff have spoken out about the pressure they are under.

A whistleblower released a dossier in which it was claimed a number of patients came to harm after long delays over the winter.

A external review later found three patients did suffer severe harm.

Management also came under fire as MPs called for top managers to step down in July.

Mr Morton said in a statement: “While I feel privileged to be the chief executive of EEAST my future plans mean I cannot commit to a further three years. I feel this is the right time to hand over to someone else.

Norman Lamb. Picture: Polly Hancock

“I wish to record my thanks to our trust chair, Sarah Boulton, and my board and executive colleagues for their unwavering support and commitment over the last three years. I also want to thank staff for their care, compassion and commitment to our patients and to supporting each other.”

Mr Morton has not confirmed his leaving date but in the post on website Need to Know, he said it would be this financial year.

In the post he also addressed staff, and said: “This trust, and in particular, you our people, have been under tremendous pressure with the ever increasing rise in demand against a background of limited resources. Everyone working on behalf of EEAST continues to work extremely hard, regardless of their role.”

Some staff welcomed the announcement. Once staff representative said: “I’ve worked with a number of chief executives over the years and the last two years have been especially difficult.

Sarah Boulton, chairman of East of England Ambulance Service Trust.

“Robert Morton’s approach to partnership working has been divisive and disingenuous. Along with many of our staff, I’m completely delighted he’s leaving. It’s the only thing we’ve ever agreed on and the best thing he’s ever done for our staff.

“I hope that the trust can now get a supportive chief executive who genuinely wants to work with elected representatives, and recognises the very big difference between actions and words when it comes to staff support.’

North Norfolk MP Norman Lamb, who was one of three MPs who called for leadership change at the trust, added: “I think the culture of the organisation is rotten, I am appalled at how people have been treated internally.”

But others were sad to see Mr Morton go.

Reacting to the news on Twitter last night Andrew Beardsley, an emergency operations manager with the trust, said: “I was genuinely saddened to read the briefing. Such an approachable, inspirational CEO who listened, acknowledged and actioned. We will all continue putting 100pc into everything we do but I do wish I wasn’t reading this.”

And Sarah Boulton, EEAST chairwoman, praised Mr Morton for his time at the trust.

She said: “For three years, [he] has successfully secured long-lasting changes on behalf of patients and staff. Together, we have found a talented and steadfast board to lead a wider team to deliver those improvements.

“‘The biggest achievement of the board he built was to secure a six-year contract with our commissioners. This means we can recruit more staff over the next three years, and increase the numbers of ambulances we have on the roads. As a result, we expect to see improvements in performance, particularly in the least densely populated areas of east of England such as Norfolk and Suffolk.

“Robert’s legacy is a great one. He has had the vision and compassion to get us into a great place, and our highly skilled board members will continue on their course to leading EEAST to becoming a high-performing trust.”